Temperature measuring devices using materials that melt at different temperatures are known. Such devices have been used for the most part as disposable clinical thermometers. For example, one type of such prior art temperature measuring device, as described in U.S. Pat. No. 3,859,856, uses a backing member and several layers of chemicals disposed in compartments on the backing member. The layers of chemicals consist of first and third layers normally separated by a second layer in each compartment. The chemicals forming the second layer having characteristics for melting at a different known temperature for each compartment. In response to the melting of the chemicals in the second layer, the chemicals in the first and third layers mix and react to form a particular color. The backing member is provided with indicia adjacent the respective compartments representative of the melting temperature of the chemical in the second layer of the associate compartment. With these devices, the sensed temperatures ascertained by reading the highest number of the indicia corresponding to the compartments having the particular color.
These prior art devices have been used primarily with human beings to measure body temperatures which generally vary within a range of 95.degree. Fahrenheit and 105.degree. Fahrenheit.
The present invention provides a simple temperature sensor which is used to indicate the temperature of water flowing through a pipe to a shower head or faucet. The sensor of the invention has a feature in that it may be readily mounted on existing showers and faucets. It also has a feature in that it is inherently simple in its construction and may be manufactured economically and sold at a relatively low price.
The embodiment of the invention to be described is one in which a series of compartments is provided along the pipe leading to the faucet or shower head, with each compartment being filled with a solid material, such as paraffin, which melts at successively higher temperatures for each compartment. The material in each compartment is normally solid. However, when the temperature of the water flowing through the pipe reaches a particular lever, the paraffin in one of the compartments melts, and becomes transparent. This enables the inner wall of the particular compartment to become visible, and to display a particular color. Then, as the temperature of the water increases, the paraffin in different compartments melts, so the back walls are sequentially displayed. The compartments are not necessarily sequential. Also, the progressive display of the back walls need not necessarily be linearly related to temperature changes.
Although the sensor will be described in conjunction with a faucet or shower in the home, it will become evident as the description proceeds, that the sensor of the invention has widespread application for both home and industrial use, for providing a simple means for indicating the temperature of a fluid flowing through a pipeline, or the temperature of a flat or curved surface.